Polychlorinated biphenyl is a fat-soluble, water insoluble hydrocarbon containing chlorine. It is extremely stable, withstanding temperatures up to 1600 degrees Fahrenheit (870 degrees Celsius) and is a fire resistant.
It has been used as a heat-transfer and insulating fluid in cooling systems and electrical equipment. Used in sealants, rubber, paints, plastics, printing ink, and insecticides.
It entered the environment as a pollutant from equipment leaks, weathered materials and interaction between food pollutants. PCB’s are not readily biodegradable and they stopped being produced in 1977. It was also banned in industrialized countries.
Polychlorinated Biphenyls (PCB)- a class of organic compounds with 1 to 10
chlorine atoms attached to biphenyls.
Biphenyls- a molecules composed of two benzene rings each containing six
carbon atoms
Structure/Destruction
This is the chemical structure of a PCB. Steps to destroying PCB’s provided by freepatentsonline.com a) Feeding sodium, naphthalene and an ether-type solvent for naphthalene to a reaction zone to cause reaction of the sodium with the naphthalene to form sodium naphthalenide, and leave an excess of at least about 50 mol. % of sodium metal. Explosions or overheating of transformers and capacitors may release significant amounts of PCB’s into the local environment. (b) After completion of step (a), feeding said PCB's to said reaction zone in an amount to provide at least about 0.5 mole of naphthalene per atom of chlorine in said PCB's and to cause reaction of the sodium naphthalenide with said PCB's to effect substantially complete dechlorination of said PCB's and form a liquid product mixture and sodium metal, (c) Forwarding said liquid product mixture to a solvent recovery zone physically separate from said reaction zone while leaving said sodium metal in said reaction zone, removing at least a major portion of said solvent from said product mixture in said solvent recovery zone and leaving a solvent-stripped mixture, (d) Recovering said removed solvent and recycling the same to said step (a), (e) Forwarding said solvent stripped mixture to a naphthalene recovery zone physically separate from both said reaction zone and said solvent recovery zone and removing naphthalene and any residual solvent from said solvent stripped mixture in said naphthalene recovery zone, and (f) Recovering said removed naphthalene and residual solvent and recycling the same to said step (a). 8. The process of claim 7 wherein steps (a), (b) and (c) are affected under an inert atmosphere. 9. The process of claim 7 wherein said steps (a) and (b) are effected at a temperature of about 20° to 25° C. 10. The process of claim 7, 8 or 9 wherein said ether-type solvent is tetrahydrofuran.
Human Health Implications
If released to the atmosphere, PCBs will primarily exist in the vapor-phase; the tendency to become associated with the particulate-phase will increase as the degree of chlorination of the PCB increases. The dominant atmospheric transformation process is probably the vapor-phase reaction with hydroxyl radicals, which has estimated half-lives ranging from 12.9 days for monochlorobiphenyl to 1.31 years for heptachlorobiphenyl. Physical removal of PCBs from the atmosphere, which is very important environmentally, is accomplished by wet and dry deposition.
EPA has found PCBs to potentially cause the following health effects from short-term exposures at levels above the MCL: acne-like eruptions and pigmentation of the skin; hearing and vision problems; spasms. PCBs have the potential to cause the following health effects from long-term exposure at levels above the MCL: effects similar to acute poisonings; irritation of nose, throat and gastrointestinal tracts; changes in liver function. There is some evidence that PCBs may have the potential to cause cancer from a lifetime exposure at levels above the MCL.
Increased liver weight and lipids and decreased liver vitamin A of male and female rats or male Japanese quail. Laying female quail did not show consistent changes, presumably due to mobilization of lipid and vitamin A for egg yolk. When egg laying was inhibited, PCB reduced liver vitamin A 50%. lsquoAroclor 1242rsquo reduced egg production, but had no effect on egg weight or eggshell thickness.
Summary
Polychlorinated biphenyl is a fat-soluble, water insoluble hydrocarbon containing chlorine. Used in sealants, rubber, paints, plastics, printing ink, and insecticides. PCB’s are not readily biodegradable and they stopped being produced in 1977. . It was also banned in industrialized countries.
If released to the atmosphere, PCBs will primarily exist in the vapor-phase; the tendency to become associated with the particulate-phase will increase as the degree of chlorination of the PCB increases. EPA has found PCBs to potentially cause the following health effects from short-term exposures at levels above the MCL: acne-like eruptions and pigmentation of the skin; hearing and vision problems; spasms. Explosions or overheating of transformers and capacitors may release significant amounts of PCB’s into the local environment.
PCBs have the potential to cause the following health effects from long-term exposure at levels above the MCL: effects similar to acute poisonings; irritation of nose, throat and gastrointestinal tracts; changes in liver function. There is some evidence that PCBs may have the potential to cause cancer from a lifetime exposure at levels above the MCL. Increased liver weight and lipids and decreased liver vitamin A of male and female rats or male Japanese quail. Laying female quail did not show consistent changes, presumably due to mobilization of lipid and vitamin A for egg yolk.
Table of Contents
Background
Polychlorinated biphenyl is a fat-soluble, water insoluble hydrocarbon containing chlorine. It is extremely stable, withstanding temperatures up to 1600 degrees Fahrenheit (870 degrees Celsius) and is a fire resistant.It has been used as a heat-transfer and insulating fluid in cooling systems and electrical equipment. Used in sealants, rubber, paints, plastics, printing ink, and insecticides.
It entered the environment as a pollutant from equipment leaks, weathered materials and interaction between food pollutants. PCB’s are not readily biodegradable and they stopped being produced in 1977. It was also banned in industrialized countries.
Polychlorinated Biphenyls (PCB)- a class of organic compounds with 1 to 10
chlorine atoms attached to biphenyls.
Biphenyls- a molecules composed of two benzene rings each containing six
carbon atoms
Structure/Destruction
This is the chemical structure of a PCB. Steps to destroying PCB’s provided by freepatentsonline.com a) Feeding sodium, naphthalene and an ether-type solvent for naphthalene to a reaction zone to cause reaction of the sodium with the naphthalene to form sodium naphthalenide, and leave an excess of at least about 50 mol. % of sodium metal. Explosions or overheating of transformers and capacitors may release significant amounts of PCB’s into the local environment. (b) After completion of step (a), feeding said PCB's to said reaction zone in an amount to provide at least about 0.5 mole of naphthalene per atom of chlorine in said PCB's and to cause reaction of the sodium naphthalenide with said PCB's to effect substantially complete dechlorination of said PCB's and form a liquid product mixture and sodium metal, (c) Forwarding said liquid product mixture to a solvent recovery zone physically separate from said reaction zone while leaving said sodium metal in said reaction zone, removing at least a major portion of said solvent from said product mixture in said solvent recovery zone and leaving a solvent-stripped mixture, (d) Recovering said removed solvent and recycling the same to said step (a), (e) Forwarding said solvent stripped mixture to a naphthalene recovery zone physically separate from both said reaction zone and said solvent recovery zone and removing naphthalene and any residual solvent from said solvent stripped mixture in said naphthalene recovery zone, and (f) Recovering said removed naphthalene and residual solvent and recycling the same to said step (a). 8. The process of claim 7 wherein steps (a), (b) and (c) are affected under an inert atmosphere. 9. The process of claim 7 wherein said steps (a) and (b) are effected at a temperature of about 20° to 25° C. 10. The process of claim 7, 8 or 9 wherein said ether-type solvent is tetrahydrofuran.Human Health Implications
If released to the atmosphere, PCBs will primarily exist in the vapor-phase; the tendency to become associated with the particulate-phase will increase as the degree of chlorination of the PCB increases. The dominant atmospheric transformation process is probably the vapor-phase reaction with hydroxyl radicals, which has estimated half-lives ranging from 12.9 days for monochlorobiphenyl to 1.31 years for heptachlorobiphenyl. Physical removal of PCBs from the atmosphere, which is very important environmentally, is accomplished by wet and dry deposition.EPA has found PCBs to potentially cause the following health effects from short-term exposures at levels above the MCL: acne-like eruptions and pigmentation of the skin; hearing and vision problems; spasms. PCBs have the potential to cause the following health effects from long-term exposure at levels above the MCL: effects similar to acute poisonings; irritation of nose, throat and gastrointestinal tracts; changes in liver function. There is some evidence that PCBs may have the potential to cause cancer from a lifetime exposure at levels above the MCL.
Increased liver weight and lipids and decreased liver vitamin A of male and female rats or male Japanese quail. Laying female quail did not show consistent changes, presumably due to mobilization of lipid and vitamin A for egg yolk. When egg laying was inhibited, PCB reduced liver vitamin A 50%. lsquoAroclor 1242rsquo reduced egg production, but had no effect on egg weight or eggshell thickness.
Summary
Polychlorinated biphenyl is a fat-soluble, water insoluble hydrocarbon containing chlorine. Used in sealants, rubber, paints, plastics, printing ink, and insecticides. PCB’s are not readily biodegradable and they stopped being produced in 1977. . It was also banned in industrialized countries.If released to the atmosphere, PCBs will primarily exist in the vapor-phase; the tendency to become associated with the particulate-phase will increase as the degree of chlorination of the PCB increases. EPA has found PCBs to potentially cause the following health effects from short-term exposures at levels above the MCL: acne-like eruptions and pigmentation of the skin; hearing and vision problems; spasms. Explosions or overheating of transformers and capacitors may release significant amounts of PCB’s into the local environment.
PCBs have the potential to cause the following health effects from long-term exposure at levels above the MCL: effects similar to acute poisonings; irritation of nose, throat and gastrointestinal tracts; changes in liver function. There is some evidence that PCBs may have the potential to cause cancer from a lifetime exposure at levels above the MCL. Increased liver weight and lipids and decreased liver vitamin A of male and female rats or male Japanese quail. Laying female quail did not show consistent changes, presumably due to mobilization of lipid and vitamin A for egg yolk.